In connection with the fabrication of integrated circuit chips, the chips undergo a number of processes, including cutting, grinding, and so on. After such processing it is necessary to dissolve the adhesive bond between the chip and a transfer tool, to which the chip is attached for processing. Additionally, it is necessary to clean the chips to remove deposits and particulates that will contaminate the chip and cause the failure of the chip or the assembly into which it is ultimately installed. During such cleaning operations, the chip is mounted in a tray, and then subjected to a cleaning solution or bath.
One problem that has been experienced in connection with polymeric cleaning trays is that, during the cleaning operation, the mechanical interactions of the chips, the tooling, and the tray may cause the material composition of the tray to break down. Therefore, fractured portions of the tray, or the fillers included in the tray material, may become a form of debris which could contaminate the chips. Additionally, some trays, which are made of plastic, may deform when they are exposed to a hot solvent bath, or hot air or nitrogen drying, thereby allowing the chips to become dislodged from the tray nests.
Another problem experienced with polymeric cleaning trays is that when they are used with an ultrasonic rinse process in high purity deionized water(18 meg-ohm), a film of micro-air bubbles forms on the plastic surfaces. This occurs as dissolved air is expelled from the water as traces of a surfactant used in the ultrasonic cleaning process are removed in the rinse cascade. As a result, the film of air bubbles erradicates any benefits of ultrasonic cleaning by inhibiting cavitation.
One potential solution to the problem of the air bubbles is to de-gas the water; however, this approach has not proven to be practically feasible. Another potential solution is to add a low concentration of a surfactant/wetting agent as a rinse aid; however, even when used in the hundredth of a percent concentration range, surfactant residue may occur.
Yet other trays that are made of metal, glass, or ceramic may cause chips placed in them to be damaged, especially if such a tray is used in connection with an ultrasonic bath. This is due to the effect of the ultrasonically induced vibration of the chips against the rigid metal, glass, or ceramic structure.
Accordingly, what is needed is a chip tray that does not cause the release of any appreciable amount of contaminants into the cleaning process of the chips. It is also desirable to have a tray that maintains its structural integrity when exposed to hot solvents, and can be used in connection with an ultrasonic or recirculating bath without damaging the chips mounted in it. And, it is desirable to have a tray that can be used in an ultrasonic rinse process using high purity deionized water, without having the formation of micro-air bubbles, and without having to use a rinse aid which may result in an accumulation of residue.